From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6DBDAC4332E for ; Tue, 19 Jan 2021 22:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6318F230FE for ; Tue, 19 Jan 2021 22:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387635AbhASOg1 (ORCPT ); Tue, 19 Jan 2021 09:36:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405040AbhASMfK (ORCPT ); Tue, 19 Jan 2021 07:35:10 -0500 Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 164BFC061574 for ; Tue, 19 Jan 2021 04:34:27 -0800 (PST) Received: by mail-wr1-x42e.google.com with SMTP id v15so15916890wrx.4 for ; Tue, 19 Jan 2021 04:34:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=dy3egPV1ka/EkZOaPATc7EsNx/78Zw3FYs2vUZuq9OU=; b=evsZNBcduUb7qJp65mS6n4i2QPR+xQy4POZWrTwxPx77Y6MwQKoj/e/V8dpgSrQkKf pnDA5+cIudYS6Id24AKDGGnBLZArqWXyf4SpAvDO8ihFDSjmi5S8OS0IXsdeSgEfQhVC dZMyTqT8W3OtlFHmN/j93o2mUX/eBtQObonmgz+5ne8jDjN8gQMebwkmePLHxZrFbXVX LA2rabkrQxfIG2aPLngyRY6T3k4T9zGraCI39n7CokXsRaw2g+L/8mlEHMSR1w7Qnb8U CIWB6r3Znl9bmzXvyI6STcehT80Dga5yGhuJo8zimw+AQGK7+x30Tp88mE3chkhUebPZ BtYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=dy3egPV1ka/EkZOaPATc7EsNx/78Zw3FYs2vUZuq9OU=; b=hgtioPElvV6IvJ39//jKXh5nwzJ3r/r6ZGtntAZGWlY8wo4yaaJJ3Mq/nALHFXD+iP lANJyrYYQ1RVbgBk64J8OQ223weoJ+p5m7YIKu4ssosbmupou+o3RDMSh27aLQb6duOn Plz3OffXxYzPZSPITEgEVzUuwzM9FxF81aaLTJuhlwPqx2rb2nrl6rOJEYeJMfGp/8Q8 P4WfI2G4RtgJhlxCrVoaWKF55rHpYtOzwxr9TAYoPr/W4LaRptsxkI8jGX9rf2VqRvap zg4l7gy5JgQJaJE7ICmTuwR9aiOjkY3V6mAWRMXlu7C8KXiob9hsg6NHRF+UajB6Fy/l mXnQ== X-Gm-Message-State: AOAM530kQhc5b++yF89jIEv/EjWa6RZxTAPeDT0f8OywOLCaPJz4aPoQ EfScYB4Ohzg5lCBAlFyiO1MRuw== X-Google-Smtp-Source: ABdhPJzuytrtz4oMI/FP+lXgZR8nD44MAhG4BGEMGEvMmaJq/MlcxUctQ8Sg7K6AdXbtI15642DvVg== X-Received: by 2002:a5d:44c8:: with SMTP id z8mr4160714wrr.366.1611059665813; Tue, 19 Jan 2021 04:34:25 -0800 (PST) Received: from google.com ([2a00:79e0:d:210:41d4:8c90:d38:455d]) by smtp.gmail.com with ESMTPSA id a17sm36904463wrs.20.2021.01.19.04.34.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jan 2021 04:34:25 -0800 (PST) Date: Tue, 19 Jan 2021 12:34:23 +0000 From: Alessio Balsini To: Rokudo Yan Cc: balsini@android.com, akailash@google.com, amir73il@gmail.com, axboe@kernel.dk, bergwolf@gmail.com, duostefano93@gmail.com, dvander@google.com, fuse-devel@lists.sourceforge.net, gscrivan@redhat.com, jannh@google.com, kernel-team@android.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, maco@android.com, miklos@szeredi.hu, palmer@dabbelt.com, paullawrence@google.com, trapexit@spawn.link, zezeozue@google.com Subject: Re: [PATCH RESEND V11 0/7] fuse: Add support for passthrough read/write Message-ID: References: <20210118192748.584213-1-balsini@android.com> <20210119110654.11817-1-wu-yan@tcl.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210119110654.11817-1-wu-yan@tcl.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jan 19, 2021 at 07:06:54PM +0800, Rokudo Yan wrote: > on Mon, Jan 18, 2021 at 5:27 PM Alessio Balsini wrote: > > > > This is the 11th version of the series, rebased on top of v5.11-rc4. > > Please find the changelog at the bottom of this cover letter. > > > > Add support for file system passthrough read/write of files when enabled > > in userspace through the option FUSE_PASSTHROUGH. > [...] > > > Hi Allesio, > > Could you please add support for passthrough mmap too ? > If the fuse file opened with passthrough actived, and then map (shared) to (another) process > address space using mmap interface. As access the file with mmap will pass the vfs cache of fuse, > but access the file with read/write will bypass the vfs cache of fuse, this may cause inconsistency. > eg. the reader read the fuse file with mmap() and the writer modify the file with write(), the reader > may not see the modification immediately since the writer bypass the vfs cache of fuse. > Actually we have already meet an issue caused by the inconsistency after applying fuse passthrough > scheme to our product. > > Thanks, > yanwu. Hi yanwu, Thank you for your interest in this change. FUSE passthrough for mmap is an extension that is already in my TODO list, together with passthrough for directories. For now I would prefer to keep this series minimal to make the review process leaner and simpler. I will start working on extending this series with new features and addressing more corner cases as soon as these changes get merged, what do you think? Thanks, Alessio